This invention relates to the field of small mechanical metallic electrical switches, i.e., micromechanical electrical switches (MEMS) of the type usable for low loss, multiple alternate circuit path-selecting, switching in a radio frequency integrated circuit device.
In view of the signal power losses often encountered with semiconductor switch devices in electronic systems operating in the microwave and gigahertz spectral regions (i.e., losses occurring in both the open and closed switch conditions) it is frequently desirable to resort to simple mechanical switching devices to accomplish signal path changes in such systems. This selection is frequently complicated however by the need to accomplish switching within the package of an integrated circuit device and in an environment wherein signals are communicated along paths comprising an electrical transmission line. Further complications arise from the often needed high operating speed combined with need for a long operating life from such switches and from the need to employ switch fabrication materials compatible with the processing steps and the specific materials used during wafer fabrication for an integrated circuit device. The actuation mechanism for such switching devices gives rise to additional areas of focus since clearly the magnetic actuation arrangements frequently used in other switching environments is all but unavailable in the limited space and limited materials environments of an integrated circuit device.
The present invention is believed to offer a mechanical switching device of the MEMS i.e., micromechanical electrical systems type, a multiple throw switch accommodating several of these complications, providing low switch input to output stray coupling and advancing the art of MEMS integrated circuit switching to a new level.
The present invention provides a die mounted externally controllable microminiature electrically energized electrical switch or relay usable within the circuitry of an integrated circuit die, and mounted within the integrated circuit package, for multiple circuit path changing purposes.
It is an object of the present invention therefore to provide an integrated circuit-compatible multiple path metallic electrical switch.
It is another object of the present invention to provide an integrated circuit-compatible metallic electrical switch of the single pole, two, three or more throws type.
It is an object of the present invention to provide an integrated circuit-compatible metallic electrical switch of the shunted single pole, single, two, three or more throws type.
It is an object of the present invention to provide an integrated circuit-compatible metallic electrical switch having any of multiple switch nodes selectably connectable with either another switch node or a signal grounding shunt.
It is an object of the present invention to provide an integrated circuit-compatible metallic electrical switch of the single pole multiple throw and either normally open or normally closed type.
It is an object of the present invention to provide an integrated circuit-compatible metallic electrical switch of the single pole multiple throw type which may be operated in a semi multiple pole mode.
It is another object of the invention to provide an electrically controllable electrical switch, a switch having certain attributes of an electrical relay or stepping switch.
It is another object of the invention to provide a multiple pole electrical switch having compatibility with the components and processes used in an integrated circuit device.
It is another object of the invention to provide an electrical switch suited to the diversion of radio frequency electrical energy among multiple paths in an integrated circuit die.
It is another object of the invention to provide a multiple node electrical switch suited for use in an integrated circuit electrical transmission line environment.
It is another object of the invention to provide an electrical switch employing either of metallic connection or capacitance coupling connection between xe2x80x9cclosedxe2x80x9d contacts of the switch.
It is another object of the invention to provide an electrical switch wherein one of the input or output contacts is multiple in nature.
It is another object of the invention to provide an electrical switch having fixed and plural movable metallic members, members all formable with integrated circuit processing techniques.
It is another object of the invention to provide an electrical switch having movable members physically restrained in each of their open and closed operating positions.
It is another object of the invention to provide a multiple node integrated circuit electromechanical switch having physical components operating life measured in the ten to the ninth power cycles and greater range.
It is another object of the invention to provide a multiple node metallic element electrical switch having operating cycle times measured in the range of microseconds.
It is another object of the invention to provide a multiple node electrical switch in which capacitance coupling through open state nodes is minimized.
It is another object of the invention to provide a multiple node electrical switch in which capacitance coupling between switch-open nodes is minimized through shunt grounding of movable switch elements in the open-switch condition.
It is another object of the invention to provide a integrated circuit-compatible multiple node micro electromechanical systems (MEMS) switch.
It is another object of the invention to provide a micro electromechanical systems (MEMS) switch of the multiple node micromachined electromechanical radio frequency type.
It is another object of the invention to provide a multiple node MEMS electrical switch having improved isolation, low electrical loss, high operating speed, low activation voltage and improved manufacturability.
It is another object of the invention to provide a multiple node MEMS electrical switch having decreased insertion loss and improved isolation at frequencies above 1 gigahertz in comparison with a comparable transistor switch.
Additional objects and features of the invention will be understood from the following description and claims and the accompanying drawings.
These and other objects of the invention are achieved by the method of performing electrical switching in a metallic conductor signal path of a radio frequency integrated circuit electrical device, said method comprising the steps of:
disposing an electrical switching assembly at an angular junction multiple conductor fan-out position along a metallic transmission line signal path in said radio frequency integrated circuit electrical device;
holding a spring urged movable metallic portion of each conductor in said multiple conductor fan-out position of said electrical switching assembly in a relaxed minimal spring tension first switching condition during quiescent state intervals of said electrical switching assembly;
changing one spring urged movable metallic conductor portion in said multiple conductor fan-out position of said electrical switching assembly into a stressed greater spring tension transient state second switching condition during selected transient actuated switch operating intervals of said electrical switching assembly;
changing said movable metallic conductor portion switching position against spring tension into said stressed greater spring tension transient state second switching condition using electrostatic force generated by an electrical potential switch control signal;
limiting spring tension urged movable metallic conductor movement arc length and movable metallic conductor element spacing gap in said electrical switching assembly during a relaxation from said second switching condition to said first switching condition using a metal stopping member selectively disposed along a switch position-changing swing path of said movable metallic conductor;
coupling radio frequency electrical signal between said movable metallic conductor-electrical switching member and a switch output conductor member using one of capacitance and ohmic coupling between said switching member and a switch output conductor member in one of said first and second switching conditions;
limiting capacitance electrical signal coupling between said movable metallic conductor electrical switching member and said switch output conductor member by one of capacitance coupled and ohmic contact grounding of said movable metallic conductor electrical switching member to a zero electrical potential metal stopping member in a remaining of said first and second switching conditions;
said first and second switching conditions comprising one of:
normally open condition in said electrical switching assembly including lowest capacity coupling between said movable metallic conductor electrical switching member and said switch output conductor member plus concurrent grounding by one of capacitance coupled and ohmic contact grounding of said movable metallic conductor member to said zero electrical potential metal stopping member; and
a normally closed condition in said electrical switching assembly including greatest capacity coupling between said movable metallic conductor electrical switching member and said switch output conductor member plus actuated switch grounding by one of capacitance coupled and ohmic contact grounding of said movable metallic conductor member to said zero electrical potential metal stopping member;
repeating said step of changing one spring urged movable metallic conductor portion in said multiple conductor fan-out position of said electrical switching assembly into a stressed greater spring tension transient state second switching condition using a selected one of said spring urged movable metallic conductor portions.